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Cardiovascular physiology > Easy Q's Ch 3-4 > Flashcards

Easy Q's Ch 3-4 Flashcards

1
Q
  1. What are the intracellular and extracellular concentrations of K+, Na+, and Ca++ in a typical cardiomyocyte at a resting membrane potential of -90Mv?
A

a. K+ in: 150 mM / out: 4mM
b. Na+ in: 20mM / out: 145mM
c. Ca++ in: 0.0001mM / out: 2.5mM

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2
Q
  1. What is a chemical gradient?
A

a. Concentration difference

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3
Q
  1. What is the equilibrium potential for Na+?
A

a. +52mV

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4
Q
  1. If the Em = -90mV, what is the net electrochemical driving force for Na+?
A

-142mV

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5
Q
  1. What is the equilibrium potential for Ca++?
A

a. +134mV

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6
Q
  1. If the Em = -90mV, what is the net electrochemical driving force for Ca++?
A

a. -224mV

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7
Q
  1. In a cardiac cell, how much do the individual ion concentrations change when ions cross the cell membrane during depolarization and repolarization?
A

a. They change very little

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8
Q
  1. Why is the Em close to the EK?
A

a. Because g’K is high in the resting cell, while g’Na and g’Ca are low

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9
Q
  1. With an action potential, in general, how many ions move across the sarcolemmal membrane?
A

a. Relatively small amount

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10
Q
  1. Which of these requires ATP in order to function?
A

a. Na+/K+-ATPase (NKA) pump, ATP-dependent Ca++ pump

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11
Q
  1. Define the term electrogenic.
A

a. An ion pump that generates a net charge flow as a result of its activity

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12
Q
  1. What are the two general types of ion channels?
A

a. Voltage gated channels: open and close in response to changes in membrane potential
b. receptor gated channels: open and close in response to chemical signals operating through membrane receptors

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13
Q
  1. What is an action potential?
A

a. APs occur when the membrane potential suddenly depolarizes and then repolarizes back to its resting state

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14
Q
  1. What is the action potential duration in a typical ventricular cardiac myocyte, and how does this compare to other muscles and nerves?
A

a. Typical nerve: 1-2ms
b. Skeletal muscle cell: 2-5ms
c. Ventricular: 200-400ms (cardiac myocyte)

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15
Q
  1. What cell types exhibit the “fast response” action potential?
A

a. Atrial and ventricular myocytes, and Purkinje fibers

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16
Q
  1. Do nonpacemaker cells have a true resting membrane potential?
A

a. Yes, it remains near the equilibrium potential for K+ because gK, through inward rectifying potassium channels is high relative to gNa and gCa in resting cells

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17
Q
  1. What is the absolute refractory period?
A

a. The cell is refractory (unexcitable) to the initiation of new action potentials

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18
Q
  1. What is the intrinsic depolarization rate of the SA node?
A

a. 100-110 depolarizations per minute

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19
Q
  1. Define positive chronotropy and negative chronotropy.
A

a. An increase in heart rate is a positive chronotropic response whereas a reduction in heart rate is a negative chronotropic response

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20
Q
  1. What are the mechanisms by which autonomic nerves alter the rate of pacemaker firing?
A

a. by changing the slope of phase 4, which determines the time required for phase 4 to reach threshold

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21
Q
  1. How could these mechanisms increase or decrease the slope of phase 4?
A

a. Sympathetic activation of the SA node increases the slope of phase 4, increasing pacemaker frequency (positive chronotropy)

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22
Q
  1. What neurotransmitter is released by the vagus nerve at the SA node?
A

a. Acetylcholine

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23
Q
  1. What does the right vagus nerve preferentially innervate?
A

a. The sinoatrial (SA)

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24
Q
  1. What does the left vagus nerve preferentially innervate?
A

a. AV node

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25
Q
  1. Define systole.
A

a. Events associated with ventricular contraction and ejection

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26
Q
  1. Define diastole.
A

a. The rest of the cardiac cycle, including ventricular relaxation and filling

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27
Q
  1. What waveform on the ECG represents the initiation of atrial systole?
A

a. P wave

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28
Q
  1. At rest, what percentage of ventricular filling is the result of atrial contraction?
A

a. 10%

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29
Q
  1. During exercise at higher heart rates, what percentage of ventricular filling is the result of atrial contraction?
A

a. 40%

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30
Q
  1. What causes the increase in atrial contractility?
A

a. Sympathetic nerve activation

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31
Q
  1. What is “atrial kick?
A

a. Enhanced ventricular filling owing to increased atrial contraction

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32
Q
  1. What is the “x descent”?
A

a. The small decline in atrial pressure following the peak of the a-wave

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33
Q
  1. Define end-diastolic volume.
A

a. The volume of blood in the left ventricle at the end of ventricular filling

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34
Q
  1. What is a normal value for end diastolic volume?
A

a. 120 mL

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35
Q
  1. What is a normal end diastolic pressure?
A

a. 8mmHg

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36
Q
  1. What heart sound is heard during atrial contraction?
A

a. Fourth heart sound, S4.

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37
Q
  1. What waveform on the ECG represents the initiation of isovolumetric contraction?
A

a. QRS complex

38
Q
  1. Describe the state (open/closed) of all heart valves during isovolumetric contraction.
A

a. All valves closed

39
Q
  1. What heart sound is heard during isovolumetric contraction?
A

a. First heart sound S1

40
Q
  1. What heart sounds are heard during the rapid ejection phase?
A

a. No heart sounds

41
Q
  1. Describe the sound created by the opening of healthy heart valves.
A

a. silent

42
Q
  1. What ECG waveform occurs during the reduced ejection phase?
A

a. T wave (ventricular repolarization)

43
Q
  1. Describe the state (open/closed) of all heart valves during the reduced ejection phase.
A

a. Aortic and pulmonic valves open, AV valves remain closed

44
Q
  1. What happens to ventricular active tension and the rate of blood ejection during the reduced ejection phase?
A

a. Ventricular active tension decreases and the rate of ejections falls.

45
Q
  1. Describe the state (open/closed) of all heart valves during the isovolumetric relaxation phase.
A

a. All valves closed

46
Q
  1. What causes these valves to close?
A

a. The total energy gradient reversal

47
Q
  1. What heart sound is heard during isovolumetric relaxation?
A

a. Second heart sound S2

48
Q
  1. Define incisura.
A

a. Deep notch

49
Q
  1. What happens to ventricular volume during isovolumetric relaxation?
A

a. Ventricular volumes remain constant

50
Q
  1. Define ejection fraction and provide normal resting values.
A

a. The stroke volume divided by the end diastolic volume. >0.55 (or 55%)

51
Q
  1. What happens to atrial volumes and pressures during isovolumetric relaxation?
A

a. Continue to increase owing to venous return

52
Q
  1. What happens to atrial pressure as soon as the AV valves open?
A

a. Rapid fall in atrial pressures as blood leaves the atria

53
Q
  1. What is the “v wave”?
A

a. The peak of the atrial pressure just before the valve opens

54
Q
  1. What is the “y descent”?
A

a. The peak is followed by the y descent, as blood leaves the atria

55
Q
  1. What is the Third Heart Sound and when is it heard?
A

a. During ventricular filling

56
Q
  1. Describe the state (open/closed) of all heart valves during the reduced filling phase
A

a. .AV vales open, aortic and pulmonic valves closed

57
Q
  1. What are normal resting systolic and diastolic blood pressures in the ventricles, aorta, and pulmonary artery?
A

a. Left Ventricle: 120/8
b. Right ventricle: 25/4
c. Aorta: 120/80
d. Pulmonary artery: 25/10

58
Q
  1. What are normal resting pressures in the right and left atria?
A

a. Right atria: 4
b. Left atria: 8

59
Q
  1. What is the equation for cardiac output?
A

a. CO = SV x HR

60
Q
  1. What are the units for cardiac output?
A

a. mL/min or L/min

61
Q
  1. What are the best indirect measures of preload?
A

a. Ventricular EDV or pressure

62
Q
  1. Define compliance.
A

a. The ratio of a change in volume divided by a change in pressure

63
Q
  1. What does a steep slope in the compliance curve indicate?
A

a. Lower compliance (hypertrophy)

64
Q
  1. What does a flat slope in the compliance curve indicate?
A

a. Higher compliance (dilation)

65
Q

What happens to ventricular compliance with an increase in ventricular pressure or volume?

A

a. Compliance decreases

66
Q
  1. How does ventricular hypertrophy affect compliance?
A

a. Decreases ventricular compliance

67
Q
  1. What is lusitropy?
A

a. Ventricular relaxation

68
Q

What is the relationship between preload and passive tension?

A

a. Increasing the preload length from points a to c increases the passive tension

69
Q
  1. What is the relationship between preload and the rate of active tension development?
A

a. AS preload increases there is an increase in active tension up to a maximal limit

70
Q
  1. At what sarcomere length does maximal active tension occur in cardiac muscle?
A

a. 2.2um

71
Q
  1. What is the normal range of sarcomere length at which normal skeletal muscle can operate?
A

a. 1.3 – 3.5 um

72
Q
  1. What is the range of sarcomere length at which normal cardiac muscle can operate?
A

a. 1.6 – 2.2 um

73
Q
  1. How does venous pressure affect preload?
A

a. An increase in venous blood pressure outside of the right atrium increases right ventricular preload

74
Q
  1. How could heart rate affect ventricular preload?
A

a. Through its influence on filling time, heart rate and ventricular filling are inversely related

75
Q
  1. How can atrial contractility increase?
A

a. Sympathetic activation

76
Q
  1. Define afterload.
A

a. The load against which the heart must contract to eject blood

77
Q
  1. What is the relationship between aortic pressure and afterload?
A

a. The greater the aortic pressure the greater the afterload on the left ventricle

78
Q
  1. How would norepinephrine increase inotropy?
A

a. By stimulating the cardiac muscle with norepinephrine

79
Q
  1. How is inotropy related to the ESPVR slope?
A

a. A decrease in inotropy = decreased ESPVR slope

80
Q
  1. What is the equation for calculating ejection fraction?
A

a. EF = SV / EDV

81
Q
  1. What is a normal ejection fraction value?
A

a. > 0.50 (50%)

82
Q
  1. What is the most important means of increasing the inotropic state?
A

a. The activity of sympathetic nerves

83
Q
  1. What equation is used to calculate myocardial oxygen consumption?
A

a. MVO2 = CBF (CaO2 – CvO2)
b. Myocardial oxygen consumption = coronary blood flow (arterial - venous oxygen contents)

84
Q
  1. What units are used to express myocardial oxygen consumption?
A

a. mL O2/100 mL blood (or, vol % O2)

85
Q
  1. What is a normal value for arterial blood oxygen content?
A

.2 mL O2/mL blood

86
Q
  1. What is a normal resting value for myocardial oxygen consumption?
A

a. 8 mL O2/min per 100g

87
Q
  1. What is a normal value for myocardial oxygen consumption during heavy exercise?
A

a. 70 mL O2/min per 100 g

88
Q
  1. What would a normal value for myocardial oxygen consumption be if the heart were arrested?
A

a. 2 mL O2/min per 100g

89
Q
  1. Why is the rate-pressure product useful?
A

a. It can be measured noninvasively

90
Q
  1. What factors lead to an increase in myocardial oxygen consumption?
A

a. Increased heart rate
b. Increased inotropy
c. Increased afterload
d. Increased preload

Cardiovascular physiology (2 decks)

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